Have you see this: http://www.google.com/trends?
Ok, you probably already have, but go look just for fun (and because I had a thought about it and it's fun to look at -- people search for some strange stuff). In a nutshell, the Google trends show you what people have been searching Google for. I'm sure they use it in their crazy ad sales bit which drives their bottom line.
We have this nice SirsiDynix system that shows me what people have been searching for, but what do I use it for? Interesting reading when I remember to check it. Not so effective, I know. But it occurs to me that this is really good data that other organizations (in this case Google) are using to drive the bottom line that I (and doubtless many of my colleagues) are ignoring.
So, do you have such data? If so, do you do something with it? Can you tell me so I can start doing it?